Hi everybody!
I need replacement transistors for some amps. So are those originals: 2SA1941 2SC5198 TOSHIBA High Power Audio Transistor,x10 bei eBay.de: Components (endet 27.02.11 03:13:26 MEZ) ?
Or is it better to replace them with "isc" ones?
Hope you can help me! I don't know what to look at when identifying original transistors.
I need replacement transistors for some amps. So are those originals: 2SA1941 2SC5198 TOSHIBA High Power Audio Transistor,x10 bei eBay.de: Components (endet 27.02.11 03:13:26 MEZ) ?
Or is it better to replace them with "isc" ones?
Hope you can help me! I don't know what to look at when identifying original transistors.
Honestly, the picture could be of the real ones, and then they will send you fakes. It is not worth the risk to buy such devices from eBay.
ISC = cheap Chinese copies that are nowhere near as good as the originals.
You could try Fairchild's FJA4213/FJA4313 which are their clones of 2SA1962/2SC5242, or Onsemi MJW3281A/MJW1302A or NJW3281G/NJW1302G. These are all good quality audio output transistors with similar specs that should work very well. Fairchild will sell you parts direct, although you should have no problem getting any of them from a good supplier.
ISC = cheap Chinese copies that are nowhere near as good as the originals.
You could try Fairchild's FJA4213/FJA4313 which are their clones of 2SA1962/2SC5242, or Onsemi MJW3281A/MJW1302A or NJW3281G/NJW1302G. These are all good quality audio output transistors with similar specs that should work very well. Fairchild will sell you parts direct, although you should have no problem getting any of them from a good supplier.
They usually lie about the ratings, and so they just fail, either straight away or after a small amount of use.
i have an amp with the output transistors already replaced with isc ones (also 1941/5198) which is running fine for half a year now. perhaps those remakes arent that bad...
i asked some german supplyers if their toshiba transistors are original. lets see, perhaps i can get some.
i'll keep it in mind but i'd like to replace the transistors with the original types.
another question: i got one amp that someone already tried to repair. the output transistors were replaced by the ones on the photo. whats that brand? or are they just very bad toshiba fakes?
another question: i got one amp that someone already tried to repair. the output transistors were replaced by the ones on the photo. whats that brand? or are they just very bad toshiba fakes?
Attachments
Definitely fakes. It wouldn't surprise me if it's a BU die in that case. Since the transistor is dead
, carefully smash the case with a hammer and post some pics here. Let's see what's hiding in there. 
Definitely fakes. It wouldn't surprise me if it's a BU die in that case. Since the transistor is dead
they arent dead but i think they arent worth keeping them so i could try smashing it.
Are these 2SC5198/2SA1941(FAIRCHILD) fake?
Fairchild Response 2011-12-14 15:25:32
Mohsen,
Good morning. According to our cross reference tool, these part numbers are a cross. You will have to compare the datasheets to see if they are an exact replacement for the C5198 & A1941. We don't offer devices that use those part numbers but they do appear to cross with our FJA4310 and FJA4210. The orderable part numbers are FJA4310OTU and FJA4210OTU
Kevin Emmons
Fairchild Customer Support
WOULD YOU HELP ME ?!
Fairchild Response 2011-12-14 15:25:32
Mohsen,
Good morning. According to our cross reference tool, these part numbers are a cross. You will have to compare the datasheets to see if they are an exact replacement for the C5198 & A1941. We don't offer devices that use those part numbers but they do appear to cross with our FJA4310 and FJA4210. The orderable part numbers are FJA4310OTU and FJA4210OTU
Kevin Emmons
Fairchild Customer Support
WOULD YOU HELP ME ?!
Fairchild are politely telling you that they don't make those Toshiba part numbers, therefore you have fakes in your pic. and very stupid fakes for that reason.
I imagine the supply of genuine parts is very difficult for you, ACOUSTICS as I am advised that even local suppliers now supply fakes, knowingly or not.
No supplier is guaranteed apart from the manufacturer direct but international distributors with reputations to protect should otherwise be your first choice for supply of critical parts. There are no bargain prices that way but there are no bargains with genuine parts anyway.
I imagine the supply of genuine parts is very difficult for you, ACOUSTICS as I am advised that even local suppliers now supply fakes, knowingly or not.
No supplier is guaranteed apart from the manufacturer direct but international distributors with reputations to protect should otherwise be your first choice for supply of critical parts. There are no bargain prices that way but there are no bargains with genuine parts anyway.
Yeah, thank God that those damn mother...
counterfeiters make mistakes such as bad, wrong markings or wrong type of cases. What makes me worry are those super-fakes out there which exactly looks like a genuine. 
Two types of "fakes" are (1) Original devices that do not match stated specifications (2) Completely different design.
If an original device does not have its maximum Vce in accordance with the specification, what is the chance it has an fT in accordance with the specification? From my experience, fake transistors sound awfully bad. But there is a completely different design from Malaysia that even tho maximum Vce is low but the sound is not too bad.
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And I'm curious about this politeness. As I said in my previous post, there are two types of fakes (1) Completely different design (2) Original devices that do not match its specification.
When an original manufacturer has off-spec production yields, where do these devices go? Destroyed? Of course not. It can be sold to third party without original manufacturer marking.
These un-marked devices, of course can be marked with different brand, or it can also be marked (illegally) with original manufacturer brand.
The question is, do you think it is not possible for the original manufacturer to legally sell their low quality products under the original brand name? May be with contract with other companies, or to be sold by their branches in third world countries?
If you come to a famous transistor manufacturer office here in Jakarta to buy your parts (all technicians go there for part replacement), the price is very low compared to the official price list. The maximum Vce doesn't match. And worse, it sounds bad.
And then I remember a thread where somebody contacted Toshiba to clarify whether they produce TO-3 2n3055/3773. These transistors are so common and have been used since the old days where counterfeiting is not yet popular.
Perhaps that famous manufacturer office is counterfeit (or more likely the people corrupt) too? Only a few manufacturers will deal direct in low quantities because it's generally a very expensive way of doing things.
Reselling defective parts under their own brand is reputation suicide. The QA sampling procedures of the large reputable companies are designed to catch issues before they make too much of an impact on their bottom line and defective batches are written off as far as the manufacturer is concerned, unless they also have a spin-off brand (e.g Semelab->Magnatec) for low quality production. Any unmarked stock that gets sold off is the work of shady QA employees or collected before the tip by others due to incomplete disposal at the factory.
This used to be common for a lot of consumer electronics too, Dodgy QA people would 'fail' slightly more devices than they should and then take these to the markets to sell off. This is why modern mega-factories like the Foxconn Apple factory these days keep extremely tight security controls on entry and exit of the facility. However at the semiconductor end of the spectrum it's likely that the companies aren't so interested in small time counterfeits (they fail quickly as well as only represent something like less than 1% of all production) because the people with big money (i.e not us DIY'ers) won't be greatly affected by it.
Reselling defective parts under their own brand is reputation suicide. The QA sampling procedures of the large reputable companies are designed to catch issues before they make too much of an impact on their bottom line and defective batches are written off as far as the manufacturer is concerned, unless they also have a spin-off brand (e.g Semelab->Magnatec) for low quality production. Any unmarked stock that gets sold off is the work of shady QA employees or collected before the tip by others due to incomplete disposal at the factory.
This used to be common for a lot of consumer electronics too, Dodgy QA people would 'fail' slightly more devices than they should and then take these to the markets to sell off. This is why modern mega-factories like the Foxconn Apple factory these days keep extremely tight security controls on entry and exit of the facility. However at the semiconductor end of the spectrum it's likely that the companies aren't so interested in small time counterfeits (they fail quickly as well as only represent something like less than 1% of all production) because the people with big money (i.e not us DIY'ers) won't be greatly affected by it.
This sounds even more stupid than the fake manufacturer's position. Whilst OEM is still in production, others are prevented from using the official type number until it is obsolete or by licensing agreements. That can otherwise only badly damage the cloner's OEM integrity.
That is so, as did National (Panasonic) & NEC, IIRC and the parts did not often appear in their catalogues. However, I think Fairchild would have admitted to such a commercial arrangement. These days they avoid it with Korean markings like KSC for 2SC or their own ID like FJP...etc. series, I believe. If the OEM part is obsolete, they often use the original 2S number in tandem with an earlier clone part number and both types are stocked - perhaps by agreement or simply applying to be registered as a supplier of that spec. part.
We fail to realise how endemic cheap fake parts are. In some countries they are the main stock that is purchased and sold in reputable businesses. It suggests the end use is not critically important, such as medical equipment or military use. If Fairchild or any other manufacturer was seen to be engaged in that trade, their marketers would have an impossible task of explaining the deception to the clients. Why would they risk supplying off-spec. parts with their own Trademark?
Sure, maybe off-spec supplies fall in that category but this is not so likely with modern Fabs who need to show profits with such cheap product anyway.
OEMs will be as polite as possible in describing other manufacturers products to avoid legal claims for damages or offending users. I think it's that simple
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